High shrinkage side by side type composite filament and a method for manufactruing the same

ABSTRACT

The present invention relates to a high shrinkage side-by-side type composite filament, wherein two kinds of thermoplastic polymers are arranged side by side type and a boiling water shrinkage (Sr 2 ) measured by the method (initial load=notified denier×1/10 g, static load=notified denier×20/10 g) of clause 5.10 of JIS L 1090 is 20 to 75% of a boiling water shrinkage (Sr 1 ) measured by the method (initial load=notified denier×1/30 g, static load=notified denier×40/30 g) of clause 7.15 of JIS L 1013. The side-by-side type composite filament is made of two kinds of thermoplastic polymers having a number average molecular weight difference (ïMn) of 5,000 to 15,000 upon spinning and the composite filament is drawn and heat-treated so as to satisfy the following physical properties: Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%): 120 to 230° C. Range of maximum thermal stress per denier: 0.1 to 0.4 g/denier

TECHNICAL FIELD

The present invention relates to a side-by-side type composite(conjugate) filament which has a high elastic property (shrinkage) evenin a filament state, and to a method for manufacturing the same.

More particularly, the present invention relates to a side-by-side typecomposite filament, which can omit a false-twisting process and canattain a fine denier filament since it has a superior crimp even in afilament state where no false-twisting treatment has been carried out,and to a method for manufacturing the same.

BACKGROUND ART

Synthetic fibers have reached the level not inferior to natural fibersin some properties owing to repeated technical development in spite oftheir short history. But, the crimp property is a property which is noteasy for synthetic fibers to exhibit and is being considered as anintrinsic property of natural fibers such as wool.

As prior art methods providing synthetic fibers with crimp propertiesare (i) a method for manufacturing a different shrinkage composite falsetwisted yarn by doubling, false-twisting and heat-setting two kinds ofsynthetic fibers (yarns) having a big difference in shrinkageproperties, (ii) a method for mixing a polyurethane fiber with anexcellent crimp property in a longitudinal direction and other syntheticfiber upon manufacturing woven or knitted fabrics, and (iii) a methodfor manufacturing a composite fiber by conjugated-spinning two kinds ofpolymers.

Of these methods, the method for manufacturing a different shrinkagecomposite false twisted yarn is a method that provides a potentialshrinkage difference by mixing, false-twisting and heat-setting twokinds of yarns having a big difference in shrinkage properties. That isto say, this method makes the best of a difference between a strain infalse twist areas and a residual strain after untwisting, in which acore yarn is deformed relatively larger than a effect yarn to be mixedand crosslinked with the effect yarn.

The different shrinkage composite false twisted yarn exhibits a goodelastic property due to a difference in elongation between core yarnsand effect yarns. But, the above method was disadvantageous in that,since the appearance of crimps is uneven and the binding force of coreyarns and effect yarns is relatively small because it is dependent uponair texturing and the like, one component yarn is released or removed bya physical force applied during a after-process or the crimping propertyis decreased.

In addition, the above method for manufacturing a different shrinkagecomposite false twisted yarn was problematic in that it is difficult toprovide a fine fineness because two or more kinds of yarns have to bemixed, and the process becomes complicated and the manufacturing cost isincreased because the two or more kinds of yarns pre-produced have to berewound and combined again.

On the other hand, the method for mixing a polyurethane fiber and othersynthetic fiber upon manufacturing woven or knitted fabrics wasdisadvantageous in that it is difficult to process because the syntheticfiber is different from the polyurethane fiber in physical and chemicalproperties. For instance, the polyester fiber is dyed using a dispersedye while a polyurethane fiber has to be dyed with an acid dye or ametal-containing dye.

Therefore, in a case that the polyester fiber and the polyurethane fiberare mixed upon manufacturing woven or knitted fabrics, there are manyproblems that, for example, it is necessary to use a chlorobenzene ormethyl naphthalene carrier for dyeing, and the final product is weak toa chlorine bleaching agent and easily hydrolysable by NaOH.

Meanwhile, a synthetic fiber manufactured by a polybutyleneterephthalate (PBT) resin has a problem that they have to undergo afalse twisting process for improving elastic property because of theirlack of shrinkage in a filament state.

Accordingly, it is an object of the present invention to provide aside-by-side type composite filament which has a superior crimp propertyeven in a filament state and thus requires no false-twisting process.

DISCLOSURE OF THE INVENTION

The present invention provides a side-by-side type composite filamentwhich has a excellent shrinkage even in a filament state which is notpassed false-twisting process. Additionally, the present inventionprovides a method for manufacturing a high elastic side-by-side typecomposite filament which has a simple process and can attain a finedenier filament since a false-twisting process can be omitted.

To achieve the above objects, there is provided a high crimp (shrinkage)side-by-side type composite filament according to the present invention,wherein two kinds of thermoplastic polymers are arranged in side by sidetype and a boiling water shrinkage (Sr₂) measured by the method (initialload=notified denier×1/10 g, static load=notified denier×20/10 g) ofclause 5.10 of JIS L 1090 is 20 to 75% of a boiling water shrinkage(Sr₁) measured by the method (initial load=notified denier×1/30 g,static load=notified denier×40/30 g) of clause 7.15 of JIS L 1013.

Additionally, there is provided a method for manufacturing a highshrinkage side-by-side type composite filament according to the presentinvention consisting two kinds of thermoplastic polymers which arearranged in side by side type, wherein two kinds of thermoplasticpolymers having a number average molecular weight difference (ΔMn) of5,000 to 15,000 are used upon spinning and the composite filament isdrawn and heat-treated so as to satisfy the following physicalproperties:

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):120 to 230° C.

Range of maximum thermal stress per denier: 0.1 to 0.4 g/denier

Hereinafter, the present invention will be described in detail.

Firstly, in the present invention, a side-by-side type compositefilament is manufactured by conjugated-spinning two kinds ofthermoplastic polymers in side by side type and then drawing andheat-treating the composite filament spun by a continuous ordiscontinuous process.

Specifically, in the present invention, a side-by-side type compositefilament can be manufactured by a spin-direct draw method which carriesout spinning, drawing and heat-treating in one process as shown in FIG.1, or a side-by-side type composite filament can be manufactured byconjugated-spinning two kinds of thermoplastic polymers in side by sidetype to prepare an undrawn or half-drawn composite filament and thendrawing and heat-treating the undrawn or half-drawn composite filamentby a discontinuous process as shown in FIG. 2.

The present invention is characterized in that two kinds ofthermoplastic polymers having a number average molecular weightdifference (ΔMn) of 5,000 to 15,000 are used upon conjugated spinning.The thermoplastic polymers include polyethylene terephthalate, etc.

The polyethylene terephthalate is produced by an ester interchangebetween ethylene glycol and terephthalic acid dimethyl, or bypolymerization between ethylene glycol and terephthalic acid. At thistime, if the polymerization time is adjusted, a number (n) of chains ofpolyethylene terephthalte can be adjusted, and a polyethyleneterephthalte with desired molecular weight can be obtained.

The number average molecular weight is a value measured by GelPermeation Chromatograpy (GPC).

If the number average molecular weight difference (ΔMn) between thepolymers is smaller than 5,000, the difference in degree of orientationbetween the polymers is insufficient and thus the shrinkage ratio of thefinal product becomes lower. If greater than 15,000, the shrinkage ratiois superior but a serious yarn swelling phenomenon occurs upon spinningdue to an excessive difference in number average molecular weight andthe yarn strength becomes lower to thereby make it difficult to set astable spinning condition.

The side-by-side type composite filament has such a shape that two kindsof thermoplastic polymers are bonded each other to form an interfacedividing the filament into halves and its cross section is a circulartype, a rectangular type, a cocoon type, etc.

The shape of the cross section is freely changeable according to a crosssection shape of a spinneret hole and a bonding method of polymers, andthe interface has a linear shape or a bow-like curved shape according toa difference in melt viscosity between polymers. Generally, a polymerhaving a low melt viscosity surrounds a polymer having a high viscosityto form an interface of a bow-like curved shape.

Meanwhile, the present invention is characterized in that the finallymanufactured composite filament is drawn and heat-treated so as tosatisfy the following physical properties:

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):120 to 230° C.

Range of maximum thermal stress per denier: 0.1 to 0.4g/denier

Preferably, the composite filament is drawn and heat-treated so that thetemperature distribution range of maximum thermal stress of the finallymanufactured composite filament is 140 to 200° C. If the temperaturedistribution range of maximum thermal stress is deviated from the aboverange, the processibility may be deteriorated or the quality of woven orknitted fabrics may be degraded.

Further, if the range of maximum thermal stress per denier is smallerthan 0.1 g/denier, the appearance of crimps is degraded, or if greaterthan 0.4 g/denier, it becomes hard to control the shrinkage.

Further, if the temperature distribution range of maximum thermal stressis smaller than 140° C. or the temperature area (Tmax, 95%) exhibiting95% of maximum thermal stress is smaller than 120° C., the shrinkagebecomes too large and thus the appearance of crimps is degraded. On thecontrary, if the temperature distribution range of maximum thermalstress is greater than 200° C. or the temperature area (Tmax, 95%)exhibiting 95% of maximum thermal stress is greater than 230° C., thedrawing stability is degraded.

In order for the drawn and heat-treated composite filament to satisfythe physical properties, a temperature of heat treatment in a secondGodet roller (6) is adjusted in the spin-direct draw method of FIG. 1,and a temperature of heat treatment in a hot plate (12) is adjusted inthe method of drawing and heat treatment by a discontinuous process asshown in FIG. 2.

The side-by-side type composite filament manufactured by theabove-mentioned method according to the present invention has two kindsof polymers arranged side by side type and tends to have a differentboiling water shrinkage from that of a typical composite fiber filament.

Generally, a synthetic fiber filament and a textured synthetic fiberyarn (false-twisted yarn) have a different condition for measuring aboiling water shrinkage from each other due to their difference in crimpproperty. Specifically, since the synthetic fiber filament has almost nocrimp, the possibility of an error according to a change of thecondition of measuring a boiling water shrinkage is relatively low. Onthe contrary, since the textured synthetic fiber yarn (false-twistedyarn) has relatively many crimps, the possibility of an error accordingto a change of the measuring condition is relatively high.

The boiling water shrinkage of the synthetic fiber filament is mostlymeasured by the method (initial load=notified denier×1/30 g, staticload=notified denier×40/30 g) of clause 7.15 of JIS L 1013 while theboiling water shrinkage of the textured synthetic fiber yarn(false-twisted yarn) is mostly measured by the method (initialload=notified denier×1/10 g, static load=notified denier×20/10 g) ofclause 5.10 of JIS L 1090.

In the side-by-side type composite filament of this invention, theboiling water shrinkage (Sr₂) measured by the method of clause 5.10 ofJIS L 1090 is 20 to 75% of the boiling water shrinkage (Sr₁) measured bythe method of clause 7.15 of JIS L 1013.

In other words, in case of the side-by-side type composite filament ofthis invention, the boiling water shrinkage (Sr₂) measured under thecondition of measuring the boiling water shrinkage of a texturedsynthetic fiber yarn (false-twisted yarn) is 20 to 75% of the boilingwater shrinkage (Sr₁) measured under the condition of measuring theboiling water shrinkage of a synthetic fiber filament.

On the contrary, in case of a general synthetic fiber filament, theboiling water shrinkage (Sr₂) measured under the condition of measuringthe boiling water shrinkage of a textured synthetic fiber yarn(false-twisted yarn) is 90 to 99% of the boiling water shrinkage (Sr₁)measured under the condition of measuring the boiling water shrinkage ofa synthetic fiber filament, which is almost not different from a boilingwater shrinkage measured regardless of a measuring method.

As described above, the side-by-side type composite filament of thisinvention is similar to a textured yarn (false-twisted yarn) in theboiling water shrinkage behavior in spite of its filament form, and ismuch superior to the textured yarn in the crimp performance.

In the present invention, various physical properties of the compositefilament and of a woven or knitted fabric are evaluated as below.

Boiling Water Shrinkage (Sr₁ and Sr₂) and Crimp Recovery Rate (CR)

The boiling water shrinkage (Sr₁) was measured by the method of clause7.15 of JIS L 1013 and the boiling water shrinkage (Sr₂) was measured bythe method of clause 5.10 of JIS L 1090. Specifically, a hank wasprepared by winding a composite filament around a creel 10 or 20 times(20 times in the method of clause 7.15 of JIS L 1013 and 10 times in themethod of clause 5.10 of JIS L 1090). An initial load and a static loadwere applied to the prepared hank to measure the length (L₀). In themethod of clause 7.15 of JIS L 1013, the initial load equals to notifieddenier×1/30 g and the static load equals to notified denier×40/30 g). Inthe method of clause 5.10 of JIS L 1090, the initial load equals tonotified denier×1/10 g and the static load equals to notifieddenier×20/10 g. The hank was heat-treated for 30 minutes in a hot waterof 100° C.±2° C., taken out, dewatered with a moist absorbent paper, andleft indoors. Then, the initial load and the static load correspondingto each of the methods were applied again to the hank to measure thelength (L₁). Continuously, the hank with initial load and static loadwas left in the water of 20° C.±2° C. and then the sample length (L₂)was measured. The static load was removed again and left and then thesample length (L₃) was measured. The measured values are substitutedinto the following formula to calculate the boiling water shrinkage andthe crimp recovery rate.${{Boiling}\quad{water}\quad{shrinkage}\quad\left( {{Sr}_{1}\quad{and}\quad{Sr}_{2}} \right)} = {\frac{L_{0} - L_{1}}{L_{0}} \times 100(\%)}$${{Crimp}\quad{recovery}\quad{rate}\quad({CR})} = {\frac{L_{2} - L_{3}}{L_{2}} \times 100(\%)}$

Elastic Property of Fabric

It was evaluated by an organoleptic test using a panel composed of 30people. If 25 or more out of 30 people judges the shrinkage of a fabricexcellent, it is represented as ⊚. If 20 to 24 people judge itexcellent, it is represented as ◯. If 10 to 19 people judge itexcellent, it is represented as Δ. If 9 or less people judges itexcellent, it is represented as x.

Temperature (Tmax) Exhibiting Maximum Thermal Stress and Maximum ThermalStress Per Denier (g/denier)

They were measured by a Thermal Stress Tester of Kanebo Engineering Co.Ltd. Specifically, a loop-shaped sample having a 10 cm length wassuspended on upper and lower hooks and then a predetermined tension[notified denier of composite filament×2/30 g] was applied to thesample. In this state, the temperature was raised at a predeterminedspeed (300° C./120 seconds). A stress change corresponding to atemperature change was drawn on a chart as shown in FIG. 3 and then atemperature area (Tmax, 95%) exhibiting more than 95% of maximum thethermal stress was obtained with the maximum thermal stress as a center.The maximum thermal stress per yarn denier was calculated by obtainingmaximum thermal stress on the chart and then substituting it into thefollowing formula.${{Maximum}\quad{Thermal}\quad{Stress}\quad{Per}\quad{Denier}} = \frac{{Maximum}\quad{Thermal}\quad{Stress}}{{Notified}\quad{denier}\quad{of}\quad{Composite}\quad{Filamment} \times 2}$

Number Average Molecular Weight (Mn) and Weight Average Molecular Weight(Mw)

They were measured using the gel permeation chromatograph (GPC) methodby the following formula:${Mn} = \frac{\sum\limits_{i = 1}^{n}\quad{Hi}}{\sum\limits_{i = 1}^{n}\quad{{Hi}/{Mi}}}$${Mw} = \frac{\sum\limits_{i = 1}^{n}\quad{{Hi} \times {Mi}}}{\sum\limits_{i = 1}^{n}\quad{Hi}}$

Hi: length of signal of detector on baseline of retention volume (Vi)

Mi: molecular weight of polymer fraction in retention volume (Vi)

N: number of data

Wherein the retention volume (Vi) is the volume of solvent consumedduring the retention time of sample component molecules in columns.

The retention time is the time taken until the sample componentmolecules enter the columns and melt out.

Since the results measured by the above method are relative values, astandard material is used in order to compensate these values. As thestandard material, mainly used is polystyrene, of which the molecularweight and the breadth of the molecular weight distribution are alreadyknown. Other kinds of standard materials also may be used on a properbasis.

The breadth of the molecular weight distribution is the width of thepeak value of the molecular weight distribution and represents thedispersity (Mw/Mn) of a target polymer material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a process for manufacturing a high crimpside-by-side type composite filament according to the present inventionby a spin-direct draw method;

FIG. 2 is schematic view of a process for manufacturing a high crimpside-by-side type composite filament according to the present inventionby drawing and heat treatment an undrawn yarn or a half-drawn yarn;

FIG. 3 is a thermal stress curve of the composite filament of thepresent invention charted in a thermal stress tester;

FIG. 4 is a micrograph showing the cross sectional state of theside-by-side type composite filament according to the present invention;

FIG. 5 is a micrograph showing the state of the side-by-side typecomposite filament before heat treatment according to the presentinvention; and

FIG. 6 is a micrograph showing the state of the side-by-side typecomposite filament after a hot water treatment (100° C.) according tothe present invention.

EXPLANATION OF REFERENCE NUMERALS FOR MAIN PARTS IN THE DRAWINGS

-   1,2: extruder 3: spinning block 4: quenching chamber 5: first Godet    roller-   6: second Godet roller 7: conjugate filament 8: draw winder-   10: undrawn yarn or half-drawn yarn drum 11: hot roller-   12: hot plate 13: draw roller 14: conjugate filament-   Tg: initial shrinkage start temperature-   Tmax: temperature exhibiting maximum thermal stress-   Tα: lower limit value of temperature area exhibiting 95% of maximum    thermal stress-   Tβ: upper limit value of temperature area exhibiting 95% of maximum    thermal stress

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is now understood more concretely by comparisonbetween examples of the present invention and comparative examples.However, the present invention is not limited to such examples.

EXAMPLE 1

A polyethylene terephthalate with a number average molecular weight (Mn)of 15,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 25,000 are conjugated-spun in side by side typeat a speed of 3,000 m/min at a temperature of 285° C. The resultingmaterial is drawn and heat-treated at a draw speed of 650 m/min and at adrawn ratio of 1.68 in a drawing and heat treatment process as shown inFIG. 2, to prepare a side-by-side type conjugate (composite) filamenthaving 100 deniers/24 filaments. The drawing and heat-treatmenttemperature (hot plate temperature) is set to 132° C. so that thecomposite filament can satisfy the following physical properties.

Maximum thermal stress per denier: 0.21 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 155° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 228° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a rapier loom using theconjugate filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type conjugate filament and of the fabric made thereof areas shown in Table 1.

EXAMPLE 2

A polyethylene terephthalate with a number average molecular weight (Mn)of 12,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 25,000 are conjugated-spun in side by side typeat a speed of 3,000 m/min at a temperature of 285° C. The resultingmaterial is drawn and heat-treated at a draw speed of 650 m/min and at adrawn ratio of 1.68 in a drawing and heat treatment process as shown inFIG. 2, to prepare a side-by-side type conjugate filament having 100deniers/24 filaments. The drawing and heat-treatment temperature (hotplate temperature) is set to 140° C. so that the composite filament cansatisfy the following physical properties.

Maximum thermal stress per denier: 0.31 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 165° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 228° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a rapier loom using theconjugate filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type conjugate filament and of the fabric made thereof areas shown in Table 1.

EXAMPLE 3

A polyethylene terephthalate with a number average molecular weight (Mn)of 16,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 28,000 are conjugated-spun in side by side typeat a temperature of 290° C. The resulting material is drawn andheat-treated in a continuous drawing and baking process as shown in FIG.1, to prepare a side-by-side type conjugate filament having 100deniers/24 filaments. The temperature of a first Godet roller is set to82° C. and the speed thereof is set to 1,800 m/min. The speed of asecond Godet roller is set to 4,815 m/min, the speed of a take-up rolleris set to 4,800 m/min, and the temperature of the second Godet roller isset to 163° C., so that the conjugate filament can satisfy the followingphysical properties.

Maximum thermal stress per denier: 0.16 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 175° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 228° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a rapier loom using theconjugate filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type conjugate filament and of the fabric made thereof areas shown in Table 1.

COMPARATIVE EXAMPLE 1

A polyethylene terephthalate with a number average molecular weight (Mn)of 21,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 25,000 are conjugated-spun in side by side typeat a speed of 3,000 m/min at a temperature of 285° C. The resultingmaterial is drawn and heat-treated at a draw speed of 650 m/min and at adrawn ratio of 1.68 in a drawing and heat treatment process as shown inFIG. 2, to prepare a side-by-side type conjugate filament having 100deniers/24 filaments. The drawing and heat-treatment temperature (hotplate temperature) is set to 118° C. so that the composite filament cansatisfy the following physical properties.

Maximum thermal stress per denier: 0.21 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 135° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 228° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a rapier loom using thecomposite filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type conjugate filament and of the fabric made thereof areas shown in Table 1.

COMPARATIVE EXAMPLE 2

A polyethylene terephthalate with a number average molecular weight (Mn)of 20,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 25,000 are conjugated-spun in side by side typeat a speed of 3,000 m/min at a temperature of 285° C. The resultingmaterial is drawn and heat-treated at a draw speed of 650 m/min and at adrawn ratio of 1.68 in a drawing and heat treatment process as shown inFIG. 2, to prepare a side-by-side type conjugate filament having 100deniers/24 filaments. The drawing and heat-treating temperature (hotplate temperature) is set to 115° C. so that the conjugate filament cansatisfy the following physical properties.

Maximum thermal stress per denier: 0.18 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 130° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 235° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a rapier loom using thecomposite filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type composite filament and of the fabric made thereof areas shown in Table 1.

COMPARATIVE EXAMPLE 3

A polyethylene terephthalate with a number average molecular weight (Mn)of 25,000 and a polyethylene terephthalate with a number averagemolecular weight (Mn) of 25,000 are conjugated-spun in side by side typeat a speed of 3,000 m/min at a temperature of 285° C. The resultingmaterial is drawn and heat-treated at a draw speed of 650 m/min and at adrawn ratio of 1.68 in a drawing and heat treatment process as shown inFIG. 2, to prepare a side-by-side type conjugate filament having 100deniers/24 filaments. The temperature of a hot roll is set to 85° C. andthe drawing and heat-treatment temperature (hot plate temperature) isset to 130° C. so that the conjugate filament can satisfy the followingphysical properties.

Maximum thermal stress per denier: 0.18 g/denier

Temperature exhibiting maximum thermal stress (Tmax): 155° C.

Temperature area exhibiting 95% of maximum thermal stress (Tmax, 95%):122 to 235° C.

Next, a five-harness satin with a warp density of 190 yarns/inch and aweft density of 98 yarns/inch is woven in a repia loom using thecomposite filament as a warp and a weft, then scoured/contracted, thendyed in a rapid dyeing machine of 125° C., and then after-processedunder a typical postprocessing condition, thereby making a fabric. Theresults of measuring various physical properties of the preparedside-by-side type conjugate filament and of the fabric made thereof areas shown in Table 1. TABLE 1 Results of evaluating physical propertiesof yarn and of fabric Physical Properties of Yarn (Sr₂/Sr₁) × shrinkageClassification Sr₁(%) Sr₂(%) 100(%) CR(%) of Fabric Example 1 15.40 6.8944.7 37.7 ⊚ Example 2 10.80 7.04 65.2 39.9 ⊚ Example 3 5.70 3.48 61.135.8 ⊚ Comparative 8.90 8.10 91.0 12.7 X Example 1 Comparative 7.17 5.8080.1 26.3 Δ Example 2 Comparative 7.68 7.80 98.1 2.30 X Example 3

In the above table, Sr₁ is a boiling water shrinkage of the compositefilament measured by the method of clause 7.15 of JIS L 1013, and Sr₂ isa boiling water shrinkage of the conjugate filament measured by themethod of clause 5.10 of JIS L 1090.

INDUSTRIAL APPLICABILITY

The side-by-side type conjugate filament of this invention is superiorin crimp property, exhibits the same properties as natural fibers and iseasy to carry out a dyeing process. Further, the present inventionreduces the manufacturing cost due to a simple manufacturing process andenables the composite filament to have a fine denier.

1. A high shrinkage side-by-side type composite filament, wherein twokinds of thermoplastic polymers are arranged side by side type and aboiling water shrinkage (Sr₂) measured by the method (initialload=notified denier×1/10 g, static load=notified denier×20/10 g) ofclause 5.10 of JIS L 1090 is 20 to 75% of a boiling water shrinkage(Sr₁) measured by the method (initial load=notified denier×1/30 g,static load=notified denier×40/30 g) of clause 7.15 of JIS L
 1013. 2. Amethod for manufacturing a high shrinkage side-by-side type compositefilament consisting two kinds of thermoplastic polymers which arearranged side-by-side type, wherein the two kinds of thermoplasticpolymers having a number average molecular weight difference (ΔMn) of5,000 to 15,000 are used upon spinning and the composite filament isdrawn and heat-treated so as to satisfy the following physicalproperties: Temperature area exhibiting 95% of maximum thermal stress(Tmax, 95%): 120 to 230° C. Range of maximum thermal stress per denier:0.1 to 0.4 g/denier
 3. The method of claim 2, wherein the compositefilament is drawn and heat-treated so that the temperature distributionrange (Tmax) of the maximum the thermal stress of the composite filamentis 140 to 200° C.
 4. The method of claim 2, wherein the thermoplasticpolymers are polyethylene terephthalate.
 5. A woven or knitted fabriccontaining the side-by-side type composite filament of claim 1.